A vehicle powertrain generates and transfers drive torque to drive at least one of a plurality of tires of the vehicle. The tires should be inflated to a predetermined (i.e., placard) pressure in order to prevent irregular tire wear and to ensure acceptable vehicle performance. Tire pressure monitoring systems have been developed to monitor the inflation level of the tires to inform a vehicle operator if a low pressure condition exists.
Traditional tire pressure monitoring systems include tire pressure sensors in each tire or use tire speed to monitor proper inflation pressure of the tires. Tire pressure sensors add undesired cost and complexity to the vehicle. Speed-based tire pressure monitoring systems measure the time between speed ring teeth on a target tire such as an ABS ring. The time is used to calculate tire speed and tire slip. Due to the nature of these calculations, traditional systems are prone to noisy data as a result of imprecise machining of speed ring teeth and micro-processor timing limitations. Although traditional tire speed based systems may operate well while traveling in a straight line, at a steady speed and on a smooth surface, they exhibit a high rate of false warnings when conditions are not optimal.